Polyester fiberfill filling material (sometimes referred to herein as polyester fiberfill) has become well accepted as a reasonably inexpensive filling and/or insulating material for filled articles, such as cushions and other furnishing materials, including bedding materials, such as mattress pads, quilts, comforters and including duvets, in apparel, such as parkas and other insulated articles of apparel and sleeping bags, because of its bulk filling power, aesthetic qualities and various advantages over other filling materials, so is now manufactured and used in large quantities commercially.
Filling materials are often of staple fiber, sometimes referred to as cut fiber in the case of synthetic fiber, which is first crimped, and is provided in the form of continuous bonded batts (sometimes referred to as battings) for ease of fabrication and conversion of staple into the final filled articles. Traditionally, bonded batts have been made from webs of parallelized (staple) fiber that preferably comprise a blend of binder fibers as well as of regular filling fibers, which can consequently be referred to as load-bearing fibers, such as poly(ethylene terephthalate) homopolymer, often referred to as 2G-T. These webs are made on a garnett or other type of card (carding machine) which straightens and parallelizes the loosened staple fiber to form the desired web of parallelized, crimped fibers. The webs of parallelized fibers are then built up into a batt on a cross-lapper. The batt is usually sprayed with resin and heated to cure the resin and any binder fiber to provide the desired bonded batt. The resin is used to seal the surface(s) of the batt (to prevent leakage) and also to provide bonding. The use of binder fiber intimately blended with the load-bearing fiber throughout the batt has generally been preferred because such heating to activate the binder material (of the binder material) can provide a "through-bonded" batt. If binder fiber is used, and if a suitable shell fabric can prevent leakage of fibers, then the resin treatment may be omitted, and is in some instances, for example, for some sleeping bags. This simplified explanation is the normal way most bonded batts are now made, because it is not expensive and is adequate for many purposes, especially when dense batts are desired. There has been a limit, however, to the ability to make lofty batts, such as are often desirable for some end-uses, by this normal procedure.
Consequently, some have preferred to use an air-laying process for preparing a lofty batt, which is then bonded. Such an air-laying process does indeed provide a way to overcome the deficiency mentioned of the normal batt-making process that has been used hitherto for making dense batts. Air-laying is, however, more costly and requires different equipment, so it has been desirable to find a less expensive way to overcome the deficiencies of the normal batt-making process without the need for more expensive equipment.
As indicated, the staple fiber is crimped for use as fiberfill. Indeed, the crimp is important in providing the filled articles with bulk and support. Generally, the crimp has been provided mechanically, by stuffer box crimping of a precursor continuous filamentary tow, as has been described in the art, as this is a reasonably inexpensive way of imparting crimp to an otherwise linear synthetic filament.